... activity betwee n tak-ing up healthy liver and taking up tumors, using eightsubsets, it is not needed to go further than 70 and 20iterations with and without using s catter modeling,respectively. ... general-purpose [MEGP] and high-energy general-purpose [HEGP] collimators(hole length 42 and 40 mm, septa thickness 1.4 and 3.2mm, hole diameter 3.4 and 4.0 mm, respectively), and amedium-energy ... tomography [PET] for the 36-,30- (cold), 28-, and 24-mm-diameter spheres: CRC = 1.09, 0.59, 0.91, and 0.69, respectively, for SPECT and CRC =1.07, 0.56, 0.84, and 0.63, respectively, for PET. However,...